Research And Implementation Of FDR Soil Moisture Sensor

Rich and accurate soil moisture information plays an important role to the study of change law on water cycle, rational utilization of water resources, precision irrigation on agriculture, forestry and animal husbandry and drought relief work. But now soil moisture detection relies mainly on the empirical estimates, having great difficulties and poor accuracy in soil moisture information acquisition in China. With the development of data communication technology, the general trend is to combine the wireless communication technology, computer networks and soil detection technology, to realize detection of soil moisture information.This paper compares different soil detection methods in China and abroad, chooses frequency domain reflectometry(FDR) to realize the soil moisture detection, and proposes the design scheme for soil moisture sensor with S3C2400 A as the embedded processor and Linux as the embedded operating system. The sensor is composed of analog signal input module, signal processing module, display module, memory module, communication module and power supply unit. The analog signal input module implements the conversion of moisture to electric signal, which consists LC resonance circuit, 128 frequency dividing circuit, waveform conversion circuit, filtering circuit and signal amplification circuit. The paper sets up the embedded Linux platform, modifies the u-boot, customs the kernel, constructs the root and transplants them to the sensor.Based on the Linux software development environment, the sensor driver and testing procedures are designed and completed.The field testing result of FDR soil moisture sensor shows that the sensor could measure and display the moisture precisely, and transmit the moisture to terminal equipment in PDU format through 3G module.It has the properties of high accuracy, high sensitivity, high real time capability and convenient operations.